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Miscible Fluids in Microgravity (MFMG) - 10.21.14

Science Objectives for EveryoneHoney and water are miscible fluids, that it, fluids that dissolve comletely in each other. Water will be injected into honey to test if it will act like an immiscible fluid, such as water being injected into oil, and spontaneously form a spherical drop. The experiment needs to be performed in weightlessness.

Science Results for Everyone

Oil and water may not mix, but honey and water do. The latter are miscible fluids, meaning they dissolve completely in each other, while the former are immiscble, which do not. Ground-based research indicates that miscible fluids sometimes can act immiscble, and this investigation tested whether that holds in weightlessness. Honey and water were used because they were already on the Station. A stream of honey injected into water broke into small drops, and an aspherical drop of water in honey spontaneously assumed a spherical shape. No behavior beyond simple diffusion was observed. This information may be important for materials processing and fluid handling in weightlessness.

The following content was provided by John A. Pojman, Ph.D., and is maintained in a database by the ISS Program Science Office.

Experiment Details

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Principal Investigator(s)

John A. Pojman, Ph.D., Louisiana State University, Baton Rouge, LA, United States

Ground-based research indicates that misciblel fluids can act like immiscible fluids. Numerical simulations of our previous MFMG experiment indicated that running the experiment longer might allow us to observe a drop of water in honey spontaneously assuming a spherical shape, as would a drop of water in oil.

We will be able to test the prediction of our numerical simulations.

The research will determine if fluid motion can occur for miscible fluids in weightlessness, even in the absence of buoyancy-driven convection.

Description
The goal of MFMG id to determine if interfacial phenomena seen with immiscible fluids can be seen with miscible fluids. The experiments will be performed with existing materials on the ISS. Honey and water were chosen as the fluids, and urine collection syringes will be used as the vessels in which the experiment will be performed. A blob of dyed water will be injected into honey. The drop of water will be imaged for several hours to determine if the water assumes a spherical shape as would be observed for immiscible fluids.

Space Applications
If we show that convection can be caused by an effective interfacial tension between miscible fluids, then this fact may be important for materials processing and fluid handling in weightlessness.

Earth Applications
The experiment may have relevance to microfluidics.

Operational Requirements
The water must be injected into the honey without air bubbles. The digital images will be the only data from the expeirment. No realtime downlink is required nor return of samples.

Operational Protocols
A blob of dyed water will be injected into honey. The drop of water will be imaged for several hours to determine if the water assumes a spherical shape as would be observed for immiscible fluids.

Miscible Fluids in Microgravity (MFMG) was a zero-upmass investigation performed on the International Space Station. The goal of MFMG was to determine if interfacial phenomena seen with immiscible fluids could be seen with miscible fluids. The experiments had to be performed with existing materials on the ISS. Honey and water were chosen as the fluids, and urine collection syringes were used as the vessels in which the experiments were performed. In March 2004 (Increment 8) Dr. Michael Foale performed four experiments under isothermal conditions to determine: If a stream of honey injected into water would exhibit the Rayleigh-Tomotika instability and break into small drops. If an aspherical drop of water in honey would spontaneously assume a spherical shape. The experiments were performed successfully. During Increment 9, Mike Fincke performed two runs in which a stream of honey was injected into water while the syringe was attached to the surface of the Commercial Generic Bioprocessing Apparatus (CGBA) at approximately 31 æC. No change in the stream shape was observed. Two more runs were performed on Increments 10 and 11 but no additional phenomena were observed. No behavior beyond simple diffusion was observed. We performed simulations with the Navier-Stokes equations plus a Korteweg stress term. We estimated that the maximum possible value of the square gradient parameter was 10–12 N for the honey-water system.

NASA Image: ISS011E07709 - ISS Expedition 11 Science Officer, John Phillips, setting up the MFMG hardware before the final session of MFMG. At the work table, Phillips slowly injected tinted water into honey for MFMG.+ View Larger Image

NASA Image: ISS011E07771 - Close up view of the MFMG syringe containing honey injected with tinted water during Expedition 11.+ View Larger Image